This invention relates to a device for fastening a blind rivet which has a rivet body and a mandrel axially extending rearwardly from the rivet body, and more specifically, to an automatic rivet loading device for use in such a device.
Ordinarily, a blind rivet fastener is used in such a manner that the mandrel of a blind rivet is inserted in a hole of a nose piece provided at the tip end of a nose housing forwardly projected from a fastener body, and is grasped by jaw means in the nose housing to be forcedly pulled rearwardly so as to set the rivet. In such a situation, it will be greatly convenient if the rivet is automatically loaded into the nose piece.
For this purpose, different automatic rivet loading devices have been heretofore proposed. For example, Japanese Patent Public Disclosure Sho No. 52-79379 discloses a device having a chuck support mounted on a nose housing movable only in a longitudinal direction. The chuck support rotatably holds a chuck body. The chuck support is adapted to be longitudinally moved by air cylinder means mounted on the device body. The chuck body has chucking pawls at its tip end. When the chuck support is in the rearmost position, the discharging end of a rivet supplying pipe mounted on the body is brought into alignment with the rear end of the chuck body to feed a rivet to the chuck pawls by pressurized air, and the rivet is held by a holding pawl. Thereafter, the chuck support is forwardly moved by the air cylinder means to its forwardmost position where the chuck body is downwardly swung through a lever by means of the air cylinder so as to align the chuck with the nose piece, and the chuck support is rearwardly moved a short distance to insert the mandrel of the rivet into the hole of the nose piece.
In the construction disclosed by the aforementioned Japanese Patent Public Disclosure Sho No. 52-79379, since the chuck body is pivotally mounted for only rotational movement against one straight pipelike chuck support, when the chuck body is downwardly swung at the front of the nose piece, in order to ensure that the rivet holding hole of the chuck pawls is brought into alignment with the hole of the nose piece, the feeding hole of the chuck body is angled to the rivet holding hole of the chuck pawls. This is apt to prevent the rivet from being surely fed to the chuck, and, when the pressure of the pressurized air is low, the rivet has a tendency to be caught by a bent portion. In addition, it is so arranged that the diameter of the holding hole of the chuck is made slightly larger than the outer diameter of the rivet body to facilitate the feeding of the rivet through a bent path to the chuck. It is for this reason that the holding pawl is provided. But, this holding pawl is not only an obstacle to rivet feeding but also is not sufficient to stably hold the rivet in the holding hole of the inner diameter larger than the outer diameter of the rivet. Further, since the rivet holding hole is at an angle to the inner path in the chuck body, a delicate adjustment is required to bring the rivet holding hole into alignment with the nose piece hole by the downward swing of the chuck body.
Accordingly, it is an object of this invention to provide a rivet loading device of simple construction which is capable of securely holding a rivet by a chuck and of securely and easily loading the rivet to a nosepiece.